Conventional methods of making absorbent articles, such as disposable diapers, are well known in the art. These methods usually rely on attaching various elements to a continuously moving substrate, such as an absorbent article, as attachment materials. The elements may include leg cuffs, containment flaps or an element which is a combination leg cuff/containment flap, such as that shown in U.S. Pat. No. 5,827,387 issued Oct. 27, 1998, to Reynolds et al. The strip of attachment material may be applied to the continuously moving substrate in a discrete or continuous manner. One problem which has been encountered is the attachment of wide band elastic materials with severe enough angular displacement to provide for proper curvilinear placement. Specifically such curvilinear placement is desired to be "anatomically correct", generally in the leg opening region of an absorbent article. Thus an absorbent article having this proper curvilinear placement is perceived as having a better fit on a body of a wearer of the absorbent article.
Curving the wide band elastic attachment material has been very difficult to accomplish and practice at high speed. Manufacturers have to settle for compromises, such as making disposable diapers having straight bands of elastic, minimal angular displacement of the elastic or reducing line speed.
The application of an elastic in a curvilinear pattern to a moving web generally requires the use of rollers for positioning the strip of elastic. U.S. Pat. No. 2,592,581 to Lorig discloses a method and apparatus for positioning a strip utilizing a roll which may be cylindrical, concave, or convex as desired to suit various installations. In U.S. Pat. No. 4,081,301 to Buell adhesive is intermittently applied to the elastic material while the elastic and web substrate are continuously run at high speed. Bourgeois, U.S. Pat. No. 3,828,367, discloses that a pair of elastic ribbons are fed to curved grooves in a roll under which a continuous web passes. As the roll with the ribbons in its grooves goes over the web, the ribbons are transferred in the contoured pattern of the grooves to the roll. One problem with a grooved roll is that it is unreliable and roping and C-folding occurs with wide band elastic ribbons. U.S. Pat No. 4,917,746 to Kons et al. discloses a method and apparatus involve a single roll moving or oscillating in a single dimension to apply each elastic ribbon to a web along an undulated path. U.S. Pat No. 4,915,767 to Rajala et al. uses a rotatable nip roll to press an elastic member against the web so the elastic member is spaced a predetermined maximum distance from a dwell line, a rotatable buffer roll above and in rolling engagement with the rotatable nip roll to cushion the rotatable nip roll against transient perturbations, and an oscillating roll, oscillating in a path transverse to a direction of web travel, above and spaced apart a predetermined length from the rotatable buffer roll. The oscillating roll applies the elastic member in a curved line on the rotatable buffer roll, with the predetermined maximum distance of the elastic member from the dwell line being directly proportional to the predetermined length between the oscillating roll and the rotatable buffer roll.
The method and apparatus of the present invention allows for high speed forming of continuously moving substrates having, as attached elements, elastic materials, such as wide band elastic materials, placed with severe angular displacement in a curvilinear pattern on a continuously moving substrate by allowing a caster roller to roll and pivot while placing the elastic materials either on a transfer roll or directly on a substrate.